The invention relates to a control system for a hitch which couples an implement to a utility vehicle and which can move the implement laterally with respect to the vehicle.
When larger implements are hitched to utility vehicles, the position of the implement must be monitored with increased vigilance. Projecting implements can swing out very far, especially when executing a curve. For example, a five-blade plow mounted on a customary three-point hitch can swing out several meters laterally during a turn. This swinging out increases the outer radius of a curved path traveled by the utility vehicle with a hitch. For example, in the case of a typical three-point hitch, the outer radius of the travel path can increase proportionally to the length of the implement. The swinging-out movement must be taken into account by the operator during curve travel in order to avoid a collision with obstacles near to the path. However, it is difficult to monitor the swinging-out of a rear mounted implement, and such collisions cannot always be avoided.
U.S. Pat. No. 3,432,184 describes a hitch device for a tractor with a triangular receiving plate to which the coupling plate of a hitch implement can be fastened. Seven longitudinally adjustable actuators run between the tractor frame and the receiving plate and are articulated by their first end to four articulation points of the tractor frame and by their other end to the receiving plate. If the tractor and the implement are not precisely aligned with one another, one of the actuators can be actuated in order to move the receiving plate laterally and perform the alignment. However, no proposals are made for overcoming the problem cited above.
An object of the present invention is to provide a hitch control system which reduces problems associated with implement swing-out during curved travel.
A further object is to provide a hitch control system which reduces the outer radius of a curved travel path of an implement coupled to a utility vehicle.
A further object is to provide a hitch control system which reduces the need to monitor an implement during curve travel, which simplified the operators task and which reduces the danger of collisions.
These and other objects are achieved by the present invention wherein a control system controls a hitch which couples an implement to a utility vehicle. The hitch includes longitudinally adjustable coupling element by means of which the implement can be shifted or pivoted in a lateral direction relative to the vehicle. The control system includes a sensor which senses turning operation of vehicle, A control unit automatically adjusts the length of the coupling elements as a function of the sensor signals. The control system automatically tracks the implement in a laterally offset direction relative to the utility vehicle as a function the steering angle, the center of gravity and/or the lateral acceleration of the rig. The implement is pushed and/or swung out laterally relative to the utility vehicle so that the implement is automatically aligned with the turning curve of the utility vehicle during travel. At the same time the overall center of gravity of the rig can be improved.
This control system significantly reduces the outer radius of travel during curve travel, especially in the case of projecting implements, so that the rig can execute smaller turning radii. The job of the operator is eased because the implement swings out less when making a curve and the danger of collisions is reduced.
Preferably, the sensor senses a turning curve value dependent on the turning radius. The coupling elements are adjusted as a function of the turning curve value so that the lateral position of the implement relative to the utility vehicle is adapted to the turning curve. Preferably, the control system takes into account the geometries of the implement and of the utility vehicle. The extent of the shifting or swinging out of the hitched implement required for an optimal radius of travel is calculated from the particular turning curve value.
The sensor preferably comprises a steering angle sensor which detects the deflection of the steering wheel or the deflection of a steered wheel. The control unit determines the particular turning radius of the utility vehicle from the steering angle of the wheels. The control unit calculates the angle of shift or swing of the implement relative to the utility vehicle required to align the implement on the turning curve of the utility vehicle, taking into account the geometry of the utility vehicle and of the implement, so that the turning radius of the entire system consisting of utility vehicle and implement is reduced.